Glaucon Challenges Socrates
To press his case, Glaucon outlines a view of justice and the value of the just life that many accept but that he himself wonders about. "They say that to do wrong is by nature good, to be wronged is bad, but the suffering of injury so far exceeds in badness the good of inflicting it that when men do wrong and are wronged by one another and taste of both, those who lack the power to avoid the one and take the other determine that it is for their profit to make a compact with one another neither to commit nor to suffer wrong; and that this is the beginning of legislation and covenants between men, and that they name the commandment of the law the lawful and the just, and that this is the genesis and being of justice (γένεσίν τε καὶ οὐσίαν δικαιοσύνης)" (Republic II.358e-359a).
"Its own advantage is what every creature by nature pursues as a good, while the convention of law forcibly diverts him to honor to equality" (Republic II.359c).
"The makers of the laws are the weaker sort of men, and the more numerous. So it is with a view to themselves and their own interest that they make their laws and distribute their praises and censures; and to terrorize the stronger sort of folk who are able to get an advantage, and to prevent them from getting one over them, they tell them, that such aggrandizement is foul and unjust, and that wrongdoing is just this endeavor to get the advantage of one's neighbors: for I expect they are well content to see themselves on an equality, when they are so inferior. So this is why by convention (νόμῳ) it is termed unjust and foul to aim at an advantage over the majority, and why they call it wrongdoing: but nature (φύσις), in my opinion, herself proclaims the fact that it is right for the better to have advantage of the worse, and the abler of the feebler. It is obvious in many cases that this is so, not only in the animal world, but in the states and races, collectively, of men--that right has been decided to consist in the sway and advantage of the stronger over the weaker" (Gorigias 483b-d).
Glaucon asks Socrates to show that this way the many conceive of justice and the good life is mistaken and that in truth the just life really is the best life.
The Search for Justice
To meet the challenge, Socrates first takes up the question of what justice is (Republic II.368c). This is what the reader might expect, given his practice in the early dialogues, but now, in the Republic, Socrates proceeds in an unexpected way. Instead of searching for what justice is, he searches for what justice is in a city and what it is in an individual. He says that he will search for what justice is in a city, because it is "bigger," and so presumably more straightforward to consider, and then, with the nature of justice in the city understood, he will search for what justice is in a human being.
This strategy can seem puzzling, but Plato's Gorgias provides some explanation. Socrates says of a human being whose soul is properly organized and ordered that "if he did what is appropriate with respect to human beings, he would be doing what is just." He also says, a few lines earlier, that "when a certain order, the proper one for each thing, is present, a thing is good."
(The Gorgias is named after an important figure in the sophistical movement. The dialogue is focused on the question of whether expertise in rhetorical persuasion is the key to the good life. Moreover, in the Gorgias, Plato uses the character Socrates in a way that marks an important departure from his practice in the early dialogues. In the Gorgias, Socrates breaks from his role as a questioner. In contrast to his practice in earlier dialogues, he is no longer primarily a counterpuncher. Now he is much more ready to say what he thinks and to argue for his views.)
(The Sophists were itinerant teachers of rhetoric primarily, but also of other subjects. Many of them came to Athens as part of political embassies, whose function was to negotiate on behalf of their home cites. Once in Athens, they stayed to fill a void in the traditional education system that had developed as Athens became powerful and her citizens became wealthy. In the law courts and elsewhere in Athenian society, the traditional education was no match for expertise in rhetorical persuasion. In this way, expertise in rhetorical persuasion appeared to many to be the key to desire satisfaction and hence to happiness and the good life. The Sophists capitalized on this appearance. They set themselves up as teachers, and the sons of the aristocracy paid huge sums of money to study with them. Because the Sophists were in the business of teaching rhetoric, they did little to disavow this common impression that skill in rhetorical persuasion was the key to the good life. They were interested in money, not truth. This put the Sophists on a collision course with Socrates. Socrates thought that the good life was a matter of having wisdom.)
Remember also that Thrasymachus demanded that Socrates not explain what justice is by supplying a synonym. He wants Socrates to say what justice is in terms of the underlying facts.
"[D]o you yourself answer and tell us what you say the just is. And don't you be telling me that it is that which ought to be, or the beneficial or the profitable or the gainful or the advantageous, but express clearly and precisely whatever you say. For I won't take from you any such drivel as that" (Republic I.336d; cf. Clitophon 409c).
These passages help explain the strategy Socrates pursues in the Republic. The suggestion is that the correct answer to the "What is justice?" question is the relatively uninformative one that justice is what is appropriate with respect to human beings. In the Republic, unlike in the early dialogues, the pursuit of a definition is no longer what drives the discussion. The search is for justice is in a city and in an individual. Socrates begins with the search for justice in the city. This is a search for the appropriate way to organize human beings into cities.
What Justice is in the City
Human beings organize themselves in cities to make their lives better. Cities provide the benefits of group living, but there are appropriate and inappropriate ways that human beings can organize themselves into a city. The appropriate organizations constitute justice in the city. These organizations function in a certain way. The question is how.
Socrates says these organizations function so that the city has three parts. It has a guardian or ruling class. The rulers are lovers of wisdom (Republic V.473d). They introduce the rules, for production and distribution of goods and for behavior of individuals in the city more generally. The city also has an auxiliary class. Its job is to enforce the rules. Finally, the city has a working class to produce the services and material goods. The rulers must rule, the auxiliaries must enforce the rules, and the workers must produce the services and material goods.
"I think our city, if it has been rightly (ὀρθῶς) founded, is completely good (ἀγαθὴν). Clearly, then, it will be wise, brave, sober, and just. So if we find any of these qualities in it, the remainder will be that which we have not found" (Republic IV.427e).
Socrates says that a just city is one in which these three parts do their respective jobs.
"The proper functioning of the working class, the guardians, and the rulers, each doing its own work in the city, ... would be justice and would render the city just" (Republic IV.434c-d).
The Lovers of Wisdom
"Cities will have no respite from evil, my dear Glaucon, nor will the human race, I think, unless lovers of wisdom rule in cities" (Republic V.473.c-d).
In a just city, the lovers of wisdom are the rulers. Why?
The rulers must know what the good is and how it applies to the circumstances. Human beings come together in cities to make their lives better. The just city is the good city. It is the city in which the citizens live good lives to the extent that this is possible. The rulers determine the details of the organization in this city.
Socrates explains the good and knowledge of it in terms of the images of the sun (Republic VI.508a-509c), line (Republic VI.509d-511e), and cave (Republic VII.514b-518d).
"For you have often heard that the greatest thing to learn is the idea of good (ἡ τοῦ ἀγαθοῦ ἰδέα) by reference to which just things and all the rest become useful and beneficial (Republic VI.505a).
"[The good] every soul pursues, and all its actions are done for its sake" (Republic VI.505d).
"Our constitution then will be perfectly ordered when such a man looks after it--that is, a man who has this knowledge [of the good]" (Republic VI.506a-b).
What Justice is in the Individual
Once they have found justice in the city, Socrates searches for justice in an individual human being.
"If you call a thing by the same name whether it is big or little, it is like in the way in which it is called the same or like. Then a just man too will not differ at all from a just city in respect of the very form of justice, but will be like it. But now the city was thought to be just because three natural kinds existing in it performed each its own function, and again it was sober, brave, and wise because of certain other affections and habits of these three kinds. Then, my friend, we shall thus expect the individual also to have these same forms n his soul, and by reason of identical affections of these with those in the city to receive properly the same appellations" (Republic IV.435a-c).
For an individual, since human beings are psychological beings, what is appropriate for a human being is a proper psychological functioning and hence a certain organization of the psychology. The human soul is tripartite. The appropriate organization of these parts is one in which reason rules and has the spirit as its ally against the appetite.
"Therefore it is fitting that the reasoning part should rule, it being wise and exercising foresight on behalf of the whole soul, and for the spirited part to obey it and be its ally" (Republic IV.441e). "These two parts... will exercise authority over the appetitive part which is the largest part in any man's soul and is insatiable for possessions. They will watch over it to see that it is not filled with so-called pleasures of the body, and by becoming enlarged and strong thereby no longer does its own job but attempts to enslave and rule over those over whom it is not fitted to rule, and so upsets everyone's whole life" (Republic IV.442a-b).
This organization of the parts is justice in a human being.
The Tripartite Theory of the Soul
The soul has three parts: "reason, "spirit," and "appetite." To argue for the existence of these parts, Socrates relies on a certain conception of desire.
Sometimes a person feels thirsty but decides not to drink. How is this possible?
According to the Tripartite Theory, there are two desires in play. One stems from appetite. It arises naturally in reaction to events in the body. In the absence of a desire from reason, this appetitive desire would motivate the person to drink. Reason, however, in the example, has the belief that in the circumstance drinking is not what should be done. If reason rules, the connection between the appetitive desire and action is interrupted. Reason overrides appetite.
"Is there something in the soul of those who are thirsty but refuse to drink, something bidding them to drink and something different, something forbidding them, that overrides the thing that bids them to drink? And doesn't the thing that forbids in such cases come into play, if it comes into play, as a result of calculation, while what drives and drags them to drink is a result of feelings and diseases? Hence isn't it right for us to claim that they are two, and different from one another? We'll call the part of the soul with which it reasons the λογιστικὸν and that with which it lusts, hungers, thirsts, and gets excited by other appetites without reason the appetitive part (ἐπιθυμητικόν), companion of indulgences and pleasures" (Republic IV.439c-d).
Socrates argues for this understanding in terms of a principle about opposite motions.
"It is obvious that the same thing will never do or suffer opposites in the same respect in relation to the same thing and at the same time. If ever we find this happening we shall know that it was not the same thing but a plurality" (Republic IV.436b-436c).
The suggestion is that desire and aversion are opposite motions of the soul. Desire is a motion toward, and aversion is a motion away. If a person is thirsty, he has a motivation to drink. If he thinks that drinking is not in his best interest, he also has a motivation not to drink. If this desire and aversion are opposite motions, then given the principle about opposite motions, it follows that this desire and aversion are motions of different things in the person. Since human beings are psychological beings, and thus do whatever they do because of states and processes in their psychology, Socrates concludes that the human psychology has at least two parts. The appetitive part of the soul has the desire, and the part of the soul that reasons has the aversion.
In addition to appetite and reason, the soul has a "spirited" part. Socrates argues that the desires in the spirited part are of kind distinct from those in the reasoning part and the appetitive part. The desires of the spirited part do not stem from reason. Further, they can be contrary to the desires of appetite.
"[I]n the soul the spirited (θυμοειδές) is a third part, by nature the helper of reason..." (Republic IV.441a).